The invention relates to multiple servo systems, in particular to the correction for surface velocity mismatch in multiple paper paths driven by separate servo systems.
For reliable and rapid movement of copy sheets through a reproduction machine, it is important to synchronize various drives and transports. This is important, in particular, in multi-drive machines such as in color machines wherein efficient registration and transfer of sheets is essential to quality output. For example, when two or more servo systems are driving the same sheet of paper, one surface is often slightly faster than the other surface (due to drive roll diameter tolerance). This causes the servo systems to oppose each other (causing a torque disturbance) resulting in image degradation. A very critical application would be the copy paper transition between a photoreceptor and a prefuser transport in a reproduction machine. In a color machine where photoreceptor motion is of extreme importance, the actual surface speed of the prefuser transport must be very close to that of the photoreceptor to avoid this image degradation.
It would be desirable, therefore, to be able to adjust one or more of the drives or servo systems in a multiple drive system to reduce opposing or counteracting forces and eliminate image degradation. It is an object, therefore, of the present invention to provide a new and improved system for compensating for the adverse effect of a drive system on the movement of a copy sheet. Another object of the present invention in multiple paper path servo systems is to be able to detect and correct for copy sheet or surface velocity mismatch. Other advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.